Standing pouches and flat bottom-type gusset bags are used as package bags for liquid or semi-liquid contents such as a jelly drink. These package bags are contrived to secure a self-standing property. Particularly, in the case of package bags for a jelly drink or the like, there is a wide use of gusset bags which can easily stand independently by the weight of the contents and are squeezed by one's hand to easily push out the contents.
As a specific example of the gusset bag, for example, a spout-attached gusset bag (for example, Patent documents 1 and 2) is known in which edge portions of a laminate film having a heat-sealable film adhered to one side thereof are heat-sealed together for the laminate film to have a cylindrical shape, the laminate film is gusset-folded so that the heat-sealed portion is positioned on the rear surface or the side surface, and an upper edge portion and a lower edge portion are heat-sealed for the laminate film to have a bag shape with a spout liquid-tightly attached to the upper edge portion. However, when the spout-attached gusset bag contains contents, the body portion swells, whereby the appearance may deteriorate.
Meanwhile, as shown in FIGS. 21A and 21B, a spout-attached gusset bag 101 (for example, Patent document 3) is known which is provided with a gusset bag 110 which is formed of a pair of flat surface portions 111, 111 facing each other and a pair of side surface portions 112, 112 connecting the side edges of both of the flat surface portions 111, 111 to each other so as to be folded toward the inside of the gusset bag 110, and a spout 120 which is attached to the gusset bag 110 to discharge the contents from the gusset bag 110.
In the spout-attached gusset bag 101, the side edge portion of the flat surface portion 111 and the side edge portion of the side surface portion 112 are heat-sealed together, and thus a side edge sealing portion 113 is formed. The side edge sealing portion 113 of the spout-attached gusset bag 101 has high rigidity because the flat surface portion 111 and the side surface portion 112 are heat-sealed together. This portion functions as a support, and thus the self-standing property of the spout-attached gusset bag 101 is improved. In addition, due to the side edge sealing portion 113 functioning as a support, the swelling of the body portion when containing contents is also suppressed.